Binary patch generation script (initial version)

Salut,
Find appended the configure'd version of a preliminary script to
faciliate patch generation following the methods defined earlier
in conversations. It's probably ugly, but it's one more quick
thing, and hey, it works!
The system variables are mostly determined by the running system,
which may not always be right - but some build.sh-like flags can
be passed to overcome this. The OpenSSL key has a default in
/etc/openssl/private/$OS.pem - e.g. NetBSD.pem - and also doesn't
need to be passed. The plist file is generated using diff if
not given; for that to work, the builddir must be kept in the
same location for both builds.
The pullup ID is required to retrieve the message. I'm not sure
there's a better way.
An example would be:
mkpatch /usr/oobj/destdir /usr/obj/destdir 423
It is certainly still going to undergo a lot of work, and your
input is really valued.
Now toast. ;-)
Tonnerre